Peeling fish, and particularly sardines, is a delicate operation which is carried out most of the time on fish as fillets. The peeling carried out automatically or manually comprises the securement of the fish on a support and cutting the skin by means of cutting elements. These mechanical cutting devices have on the whole difficulties in adjusting the level of the blades, knives and conveyors, which gives rise to loss of quality and lower weight production of the peeled fillets by these processes.
Other processes, such as that described in GB-A-2 116 829, consist, after superficial heating of the skin of the fish, in immersing this latter in an aqueous medium and drying it by the aid of brushes constituted by rotating rollers. In GB-A-2 160 757, the brushing is replaced by pulverization by cold water jets under pressure.
A last process applied industrially today consists in putting the skin of the fish in contact with a surface of a refrigerated drum and separating the quick-frozen skin by means of a continuous ribbon knife.
All the processes and apparatus described above are applied to preferably large fish in the form of fillets and whose size must be relatively homogeneous to avoid qualitative and quantitative loses that are too great.
In the case of fruits such as peaches, it is known to effect a chemical pretreatment by immersion in dilute caustic soda to which are added wetting agents, at a temperature of the order of 90.degree. C., then peeling by passage between abrasive rubber discs. This process, involving the use of chemical agents and a relatively high temperature, is very deleterious to the nature of the product obtained.
As to vegetables such as tomatoes, it is usual to use chemical and/or steam processes. There again, the peeled product obtained is generally degraded and the process is not suitable for the peeling of fragile food products.
There is also known, from JP-A-59.210877, a process for peeling tomatoes consisting in preheating the tomatoes and placing them in contact with a current of hot air while causing them to rotate. Such a process requires a large and expensive installation and is not applicable to flat and/or elongated objects such as fish fillets.
In certain particular cases such as chestnuts or onions, it is known to burn the skin and then remove it by blowing compressed air or by aspiration. Such a process is not of general application.